PPM Systems & FS_THR_VALUE woes


I just upgraded to 3.3.1 and was having some issues with FS_THR_VALUE using a TBS Crossfire which cannot have it’s MIN Throttle Value trimmed below 988 using PPM ( didn’t try PWM so it might work there ) - Luckily the Crossfire offers the choice to use Failsafe CUT instead of Failsafe Stick Position which still required some trial and error to get it working while I was still running 3.2.1 by setting FS PWM to 0 which autocorrected to 800.

Enter the 3.3.1 - What basically happened here was the following:
[li]Upgrade to 3.3.1[/li]
[li]FS_THR_VALUE Error appeared - Copter wouldn’t arm.[/li]
[li]Performed RC Calibration.[/li]
[li]FS_THR_VALUE Error still in effect.[/li]
[li]Increased FS PWM to 950 - I was reading that the FS PWM Value had to be 910 or more.[/li]
[li]FS_THR_VALUE Error disappeared - Even in flight the motors would shut down when the Throttle Stick was put at lowest position and immediately start up again when moved slightly up.[/li][/ol]

Not very comfortable with this I decided to try an ESC Calibration:
[ol][li]Performed ESC Calibration.[/li]
[li]FS_THR_VALUE Error still gone - Motors would now keep spinning when Throttle Stick was put at lowest position even when on the ground.
Until the 5sec Disarm kicks in.[/li][/ol]

Can anyone explain this or maybe confirm this being the proper way of solving it and not just a fluke?
I mean I was kinda lucky with the ESC Calibration and it solving it for now but I’d still like to understand what has happened =)